This invention relates generally to surgical instruments, and more particularly, to microsurgical instruments.
Microsurgical systems are gaining ever-increasing acceptance in the surgical community for performing precise, minimum invasive surgery for various parts of the body. One particularly widespread microsurgical application is in the field of ophthalmology, and various manufacturers now produce opthalmic microsurgical systems. Examples of such syststems are the Model 8000V system of Cavitron/Kelman and the Occutome II/Fragmatome II system of Cooper Medical Devices Corporation. Such systems have been used for performing anterior as well as posterior chamber surgery.
In either type of surgery, a remote handpiece having a small tool is used to either cut or mascerate the eye tissue while an irrigation or infusion liquid, such as Ringer solution, is brought to the situs of the surgery within the eye. The cut or mascerated tissue (detrius) is carried away from the surgical situs by a suction conduit or tube (which may or may not be connected to the tool) to some sort of collection vessel, e.g., a bag or bottle, located at the instrument or remote therefrom.
The suction produced in the suction conduit or line is usually controlled by the surgeon, via some switch means, e.g., a foot switch, so that the vacuum can be interrupted, when desired, during the surgery. In many applications it is also desireable to halt the flow of the infusion liquid upon the interruption of the suction line. The means for interrupting the infusion usually consists of an on/off valve or switch in the infusion line.
Heretofore, various prior art microsurgical systems have been arranged for receipt of portions of the suction line into a pinch valve in the instrument so that when the suction flow is to be stopped, the pinch valve occludes the line.
It will be appreciated by those skilled in the art that when the suction line is occluded, the inertia of the material within the line upstream of the occlusion point continues to produce suction at the entrance to the suction conduit. This residual vacuum can present substantial hazard in ophthalmic surgery applications, and particularly in anterior surgery applications since the anterior chamber is of much smaller volume than the posterior chamber. Thus, the residual or continued vacuum at the entrance to the suction line after the surgeon acts to interrupt the suction can result in the excessive evacuation of fluid from the anterior chamber or can result in the snagging and concomitant damage of delicate eye tissue.
In view of the foregoing and in the interest of surgical efficiency and patient safety, it is of considerable importance that there be precise control of the start-up and interruption of the vacuum in the suction line, while also insuring that upon the vacuum interruption, the suction line is neutralized to overcome any residual suction and inertial effects. In this regard, some microsurgical systems have incorporated venting means in the instrument itself to vent the suction line to the atmosphere when the suction line is occluded. Such systems also make use of replaceable hydrophobic filter means which is disposed in the instrument to prevent any material in the collection vessel from gaining ingress into the means which produce the vacuum, e.g., the vacuum pump.
While prior art microsurgical systems and techniques are generally suitable for their intended purposes, they leave much to be desired from the standpoint of simplicity of construction and use, and efficiency of operation. For example, with the prior art microsurgical systems described heretofore, it is necessary to connect the individual components making up the system, e.g., the filters, valves, collection bags or bottles, tubing, etc., to the instrument. Such preoperative setup procedures require substantial time, are complicated, messy and susceptible to error.